Toxicity of two lipid emulsions on human lymphocytes and neutrophils

Introduction

The incorporation of lipid emulsions in parenteral diets is a requirement for energy and essential fatty acid supply, and may prevent many metabolic disturbances associated with intravenous feeding amino acids and glucose alone in critically ill patients. For different parenteral fat emulsions, a significant impact on the immune system has been shown. In this study, the toxicity of soybean oil-based emulsion and olive oil-based emulsion on leukocytes from healthy volunteers was investigated.

Methods

Twenty-four volunteers were recruited and blood samples were collected before infusion of a soybean oil-based emulsion or olive oil-based emulsion, immediately afterwards and 18 hours later. The cells were studied immediately after isolation, and after 24 hours or 48 hours in culture. The following determinations were made: composition and concentration of fatty acids in plasma, lymphocytes and neutrophils, and lymphocyte proliferation. The toxicity was determined by plasma membrane integrity, DNA fragmentation, phosphatidylserine externalization, mitochondrial depolarization, production of reactive oxygen species and neutral lipid accumulation.

Results

Both lipid emulsions decreased lymphocyte proliferation and induced cell death, but the effects of soybean oil-based emulsion were more pronounced. Soybean oil-based emulsion provoked apoptosis and necrosis, whereas olive oil-based emulsion caused neutrophil and lymphocyte necrosis only. Evidence is presented that lipid emulsion is less toxic to neutrophils than to lymphocytes. The mechanism of cell death induced by this lipid emulsion involved mitochondrial membrane depolarization and neutral lipid accumulation, but did not alter production of reactive oxygen species.

Conclusion

Olive oil-based emulsion can be an alternative to soybean oil-based emulsion, avoiding leukocyte death and the susceptibility of patients to infections.